I hope this will not start a flamewar: I noticed that, despite being widely used, ref=* is not rendered for landuse=forest. I assumed this was used for parcel (compartment) numbers, as this tag seems to fit the definition of a parcel number; nevertheless, I saw on a Github issue of the main style that this usage of ref=* on landuse=forest was unproven and that, consequently, ref=* should not be assumed to contain the parcel number. Besides, it seems that the wiki doesn't document this use of ref=*. Making some use of Overpass turbo seems to indicate that ref=* is indeed used for parcel numbers; there is also boundary=forest_compartment relations, but they seem to be far less used, and mainly in Russia. I would like to document this specific use of ref=*, but, before, are there use cases where ref=* is used with landuse=forest for something else, or are such uses errors, or marginal enough to ignore them?

The fundamental problem with forest + ref is that you then have to break up a named forest into individual parcels and then have to use some complicated mechanism such as a site relation to restore the name. Further individual forests may also have identifiers in national forest inventories. Furthermore the ref combination is not extensively used in Europe and when it is it applies to the whole forest (one just SW of Bordeaux, one in Swiss commune of Sembrancher, around Sundsvall, Sweden) or is not obviously an identifier (in Trentino-Adige, Tirol). I presume many of the actual usages are imports.